U.S. patent application number 11/671717 was filed with the patent office on 2007-10-18 for electrical machine.
Invention is credited to Ralph Dammertz, Juergen Wiker.
Application Number | 20070241624 11/671717 |
Document ID | / |
Family ID | 38050384 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070241624 |
Kind Code |
A1 |
Wiker; Juergen ; et
al. |
October 18, 2007 |
ELECTRICAL MACHINE
Abstract
An electrical machine has an armature with armature grooves for
accommodating an armature winding and which is non-rotatably
supported on an armature shaft, wherein at least one
heat-conducting element is provided in the region of at least one
end face of the armature.
Inventors: |
Wiker; Juergen;
(Hangzhou/Bing, CN) ; Dammertz; Ralph; (Mt.
Prospect, IL) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
38050384 |
Appl. No.: |
11/671717 |
Filed: |
February 6, 2007 |
Current U.S.
Class: |
310/60R ;
310/52 |
Current CPC
Class: |
H02K 1/32 20130101; H02K
9/06 20130101; H02K 9/22 20130101 |
Class at
Publication: |
310/060.00R ;
310/052 |
International
Class: |
H02K 9/06 20060101
H02K009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2006 |
DE |
10 2006 014 499.6 |
Claims
1. An electrical machine, comprising an armature shaft; an armature
winding; an armature provided with armature grooves for
accommodating said armature windings and non-rotatably supported on
said armature shaft; and at least one heat-conducting element
provided in a region of at least one end face of said armature.
2. An electrical machine as defined in claim 1; and further
comprising a fan wheel which is non-rotatably supported on said
armature shaft and is connected with said armature in a thermally
conductive manner via said at least one heat-conducting
element.
3. An electrical machine as defined in claim 2, wherein said heat
conducting element is configured as an integral element with said
fan wheel.
4. An electrical machine as defined in claim 2, wherein said fan
wheel includes recesses in which said at least one heat-conducting
element engages.
5. An electrical machine as defined in claim 1, wherein said
armature includes recesses in which said at least one
heat-conducting element engages.
6. An electrical machine as defined in claim 1, wherein said
heat-conducting element engages in said armature grooves.
7. An electrical machine as defined in claim 1, wherein said
heat-conducting element is configured so that it is bonded with
said armature using a heat-conducting material.
8. An electrical machine as defined in claim 1, wherein several
said heat-conducting elements are provided in the region of said at
least one face of said armature.
9. An electrical machine as defined in claim 8, wherein said
heat-conducting elements are configured as elements selected from
the group consisting of pins and segments.
10. An electrical machine as defined in claim 1, wherein said
heat-conducting element is configured as a sleeve and is
non-rotatably mounted on said armature shaft.
11. An electrical machine as defined in claim 1, wherein said
heat-conducting element is configured as a tube and connected with
an outer circumference of said armature
Description
CROSS-REFERENCE TO A RELATED APPLICATION
[0001] The invention described and claimed hereinbelow is also
described in German Patent Application DE 102006014499.6 filed on
Mar. 29, 2006. This German Patent Application, whose subject matter
is incorporated here by reference, provides the basis for a claim
of priority of invention under 35 U.S.C. 119(a)-(d).
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an electrical machine, in
particular a universal motor.
[0003] Universal motors are used widely, e.g, in power tools.
Since, with universal motors, electric current flows through the
armature winding and the excitation winding, a great deal of heat
is produced, which gradually heats up the entire motor. To prevent
damage that could be caused by the motor heating up, it must be
ensured that the motor is cooled adequately. With power tools, air
is drawn in from the outside, e.g., through a fan wheel, for
cooling, as described, e.g., in DE 102 56 805 A. The fan wheel is
mounted non-rotatably on the armature shaft between the armature
and gearbox. When the fan wheel rotates, it generates an air flow
which flows axially through the power tool and carries heat to the
outside.
[0004] To achieve good cooling, as much as air as possible must be
transported through the power tool. High air throughput means a
high flow rate, however, which can be associated with undesired fan
noises under certain circumstances. In addition, when the cooling
air flows through the power tool, it only passes over the surface
of the armature and the stator. With universal motors with a small
armature diameter in particular, the surface of the armature and
the stator is correspondingly small, so that a relatively small
amount of heat can be given off to the cooling air by the armature
and the stator. Cooling using a fan wheel is therefore
inadequate.
SUMMARY OF THE INVENTION
[0005] Accordingly, it is an object of the present invention to
provide an electrical machine, which is a further improvement of
the existing electrical machines.
[0006] In keeping with these objects and with others which will
become apparent hereinafter, one feature of the present invention
resides, briefly stated, in an electrical machine, comprising an
armature shaft; an armature winding; an armature provided with
armature grooves for accommodating said armature windings and
non-rotatably supported on said armature shaft; and at least one
heat-conducting element provided in a region of at least one end
face of said armature.
[0007] The electrical machine according to the present invention
has the advantage that more heat is given off by the armature,
since its surface is larger due to at least one heat-conducting
element which is located at least in the region of one of the two
end faces of the armature. The heat-conducting element has the
function of carrying heat away from the armature. The
heat-conducting element is therefore made of a thermally conductive
material, in particular a metal, e.g., aluminum or sheet steel, and
it is connected with the armature in a thermally conductive manner.
According to the present invention, a single heat-conducting
element or several heat-conducting elements are provided. A
heat-conducting element can be located on the end face of the
armature facing the commutator and/or on the end face diametrically
opposed thereto.
[0008] The thermally conductive connection of a heat-conducting
element with the armature can take place via bonding using a
thermally conductive material. The thermally Conductive material
for the bonded connection can be, e.g., a thermally conductive
adhesive mass or resin.
[0009] In addition or as an alternative thereto, to provide a
thermally conductive connection, the armature can include recesses
in which the heat-conducting element engages. The armature is
typically composed of an armature laminated core with armature
grooves formed between adjacent armature teeth. The armature also
has a central opening for accommodating an armature shaft. Recesses
provided for engagement of the heat-conducting element in the
armature can be, e.g., bore holes near the armature teeth, e.g., in
the tooth shafts or tooth crests.
[0010] In a further alternative embodiment, the heat-conducting
element engages in the armature grooves. The heat-conducting
element can be inserted, e.g., before the armature winding is wound
in the armature grooves. The heat-conducting element can also be
inserted in the armature grooves before the armature winding is
wound, e.g., in that it engages in the armature grooves in the
manner of a slot wedge.
[0011] In a first embodiment, the heat-conducting element is
tubular and is installed at least on an end face along the outer
circumference of the armature. The heat-conducting element projects
over the end face of the armature. In this manner, the
heat-conducting element enlarges the heat-dissipating surface of
the armature. A tubular heat-conducting element of this type can
also include impeller-like heat-conducting surfaces. They also
increase the heat-conducting surface of the armature. The
additional, impeller-like surfaces can be located, e.g., on the
outer circumference of a tubular heat-conducting element in the
axial direction.
[0012] In a preferred embodiment, the electrical machine can
include a housing, a stator, an armature with armature grooves for
accommodating an armature winding, and a fan wheel for cooling the
electrical machine. The armature and the fan wheel are
non-rotatably supported on an armature shaft. In particular, the
fan wheel is located on the end face of the armature facing away
from the commutator. In particular, the fan wheel is located on the
armature shaft directly next to the armature. The fan impellers
face the armature. When the fan wheel rotates, it generates an air
flow which flows axially through the electrical machine. The air
flow is produced by drawing cold air into the interior of the
housing from the outside via inlet openings located on the side of
the armature facing away from the fan wheel. After the cooling air
has flowed axially through the electrical machine, the heated air
is dissipated to the outside via outlet openings located, e.g.,
near the fan wheel.
[0013] In the preferred embodiment, the fan wheel is connected with
the armature in a thermally conductive manner via at least one
heat-conducting element. Via the heat-conducting connection of the
armature with the fan wheel using at least one heat-conducting
element, the surface of the armature--which serves as a cooling
surface--is enlarged considerably, since the fan wheel--in addition
to the heat-conducting element--acts as a dissipator. As a result
of the increased heat dissipation, higher motor output is attained
with the same volume of air, i.e., with the same fan wheel
diameter.
[0014] At least one heat-conducting element is provided, which is
connected with the armature and the fan wheel in a thermally
conductive manner. The fan wheel and the heat-conducting element
are made of a material with good thermally conductive properties,
e.g., aluminum or sheet steel. The design of the armature
preferably includes an armature laminated core. The connection
between the heat-conducting element and the fan wheel, and between
the heat-conducting element and the armature must also be thermally
conductive in design.
[0015] In one embodiment, the heat-conducting element is integral
with the fan wheel. This has the advantage that the heat-conducting
element need not be manufactured as a separate component and in a
separate working step with the fan wheel.
[0016] In an alternative embodiment, the fan wheel includes
recesses in which the heat-conducting element engages, to connect
the heat-conducting element with the fan wheel. To this end,
suitable connecting elements such as pegs can be provided on the
heat-conducting element, which are inserted in matching recesses in
the fan wheel.
[0017] In a further embodiment, the heat-conducting element is
bonded with the fan wheel using a thermally conductive material,
e.g., a thermally conductive adhesive mass.
[0018] The various types of connections of the heat-conducting
element with the fan wheel and with the armature can also be
combined, of course. For example, the heat-conducting element can
engage in recesses of the armature and also be connected therewith
in a bonded manner, e.g., using a thermally conductive adhesive
mass.
[0019] In a simple embodiment, the heat-conducting element which
connects the armature with the fan wheel can be a pin, a segment,
or the like. Several heat-conducting elements in the form of pins,
segments, or the like can also be provided, which are distributed
evenly over the surface of the armature, for example. The pins,
segments, or the like can be provided as individual heat-conducting
elements and can be connected individually with the fan wheel and
the armature. Several pins, segments, or the like can also be
connected with each other, e.g., via an annular element. This can
make it easier to attach the pins, segments, or the like to the fan
wheel and the armature, and it can enlarge the heat-dissipating
surface.
[0020] According to a further embodiment, the heat-conducting
element is designed as a sleeve which is non-rotatably mounted on
the armature shaft. The sleeve, which is made of thermally highly
conductive material, is located directly on the armature shaft and
is, e.g., pressed or inserted under the armature onto the armature
shaft. The sleeve is so long that it extends below the armature on
the end face of the armature facing the fan wheel and can be
connected with the fan wheel in a thermally conductive manner,
e.g., via pressing, screws, or adhesion. As an alternative, the
sleeve can also be integral with the fan wheel. In this case, the
sleeve is also fastened under the armature to the armature
shaft.
[0021] In a further embodiment, the heat-conducting element is
tubular and is connected with the outer circumference of the
armature. The tubular heat-conducting element can be integral with
the fan wheel. Or, it can be inserted into an annular recess of the
fan wheel. It is also possible to mount the tubular heat-conducting
element on the fan wheel using a heat-conducting material, e.g., a
resin or an adhesive mass. The diameter of the tubular
heat-conducting element is selected depending on the outer diameter
of the armature. For example, the heat-conducting element can be
slid onto the armature on the end face of the armature facing the
fan wheel, and can be connected with the armature, e.g., in a
bonded manner using an adhesive mass. A tubular heat-conducting
element enlarges the heat-dissipating surface considerably.
[0022] The various embodiments of heat-conducting elements can be
used individually or in combination.
[0023] The novel features which are considered as characteristic
for the present invention are set forth in particular in the
appended claims. The invention itself, however, both as to its
construction and its method of operation, together with additional
objects and advantages thereof, will be best understood from the
following description of specific embodiments when read in
connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 shows an electrical machine according to the related
art, in a longitudinal sectional view
[0025] FIG. 2 shows a first embodiment of the inventive electrical
machine, in a longitudinal sectional view
[0026] FIG. 3 shows a second embodiment of the inventive electrical
machine, in a longitudinal sectional view
[0027] FIG. 4 shows a third embodiment of the inventive electrical
machine, in a longitudinal sectional view
[0028] FIG. 5 shows a fourth embodiment of the inventive electrical
machine, in a longitudinal sectional view
[0029] FIG. 6 shows a further embodiment of an armature with a
heat-conducting element.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] FIG. 1 shows an electrical machine 10 according to the
related art, in a longitudinal sectional view Only those components
of electrical machine 10 which are essential to the present
invention will be described below. Electrical machine 10 includes a
housing 20 in which a stator 30 is non-rotatably located. An
armature 40 with armature teeth 44 and armature grooves 42 located
between them for accommodating an armature winding (not shown) is
non-rotatably mounted on an armature shaft 22. A commutator 25 is
also mounted non-rotatably on armature shaft 22, on an end face of
armature 40.
[0031] A fan wheel 60 for cooling electrical machine 10 is also
mounted non-rotatably on armature shaft 22, on the other end face
of armature 40. The fan wheel includes fan impellers 62 which face
armature 40. To produce an axial air flow (indicated via arrow 64
in FIG. 1) in electrical machine 10, inlet openings 24 are provided
in housing 20 near the end face opposite fan wheel 60, and outlet
openings 26 are provided near the end face of armature 40 facing
fan wheel 60. When fan wheel 60 rotates, air (indicated via arrow
65 in FIG. 1) is drawn into housing 20 from the outside through
inlet openings 24, and is blown out of housing 20 through outlet
openings 26 (indicated via arrow 66 in FIG. 1). Axial air flow 64
flows through stator 30 and air gap 28 between stator 30 and
armature 40. The cooling air flows along the surface of armature
40. Electrical machine 10 can be a universal motor, for example,
and include a stator 30 with a field winding (not shown).
[0032] In FIG. 2 and in subsequent FIGS. 3 through 5, identical or
similar components are labelled with the same reference numerals as
in FIG. 1. In addition, only those components which are essential
to the present invention are shown in FIG. 2 and in subsequent
FIGS. 3 through 5.
[0033] FIG. 2 shows a first embodiment of a heat-conducting element
in the form of a pin 71. Pin 71 is connected in a thermally
conductive manner with fan wheel 60 and armature 40. Fan wheel 60
includes a recess 67 for accommodating pin 71. Armature 40, which
is composed of an armature laminated core, also includes a recess
46 for accommodating pin 71. Recess 67 in fan wheel 60 and recess
46 in armature 40 can be bore holes, for example. Recess 46 in the
armature can located, e.g., near an armature tooth, in particular
the tooth shaft or tooth crest (not shown). Heat-conducting pin 71
therefore connects armature 40 with fan wheel 60 and forms a heat
bridge which carries heat away from armature 40 to fan wheel 60.
Pin 71--as is fan wheel 60--is made of a thermally highly
conductive material, e.g., aluminum or sheet steel. Pin 71 can be
designed with any cross-sectional shape or with any diameter.
Advantageously, several pins 71 are distributed over the surface of
armature 40. Pins 71 can be connected individually with fan wheel
60 and armature 40, or they can be connected with each other, e.g.,
via a ring.
[0034] A second embodiment of a heat-conducting element is shown in
FIG. 3. This is a peg 72 which is connected in a thermally
conductive manner via engagement--in a recess 67--with fan wheel
60. Peg 71 is connected in a thermally conductive manner with
armature 40 by inserting it into an armature groove 42 before an
armature winding (not shown) is installed. Peg 71 is therefore
located at the base of armature groove 42. On end face 48 of
armature 40, peg 71 is U-bent toward armature shaft 22 and extends
essentially along or parallel with armature shaft 22 toward fan
wheel 60 until peg 71 engages in recess 67. Peg 71 therefore also
serves as a heat bridge and carries heat away from armature 40 to
fan wheel 60. Several pegs 71 can also be provided, each of which
is inserted in an armature groove 42.
[0035] Heat-conducting elements, which are inserted in armature
grooves 42 as is peg 71, according to FIG. 3, are particularly
advantageous, because it is not necessary to provide recesses 46 in
armature 40 to create a thermally conductive connection with
armature 40. With a thermally conductive element such as peg 71,
the magnetomotive force of armature 40 is therefore not disturbed
by the engagement of the heat-conducting element in recess 46 of
armature 40. In addition, heat-conducting elements such as peg 71
do not make the winding procedure unnecessarily difficult when the
windings are inserted in armature grooves 42.
[0036] FIG. 4 shows a third embodiment of a heat-conducting element
in the form of a sleeve 73. Sleeve 73 is made of a thermally highly
conductive material. It is installed directly on armature shaft 22,
e.g., it is pressed or inserted thereon. To establish a thermally
conductive connection, sleeve 73 engages in a recess 67 of fan
wheel 60 and can be connected with fan wheel 60, e.g., via
pressing, bonding, or screws. It can also be integral with fan
wheel 60 (this design is not shown). Sleeve 73 also extends along
armature shaft 22, preferably along the entire length of armature
40. Armature 40 is therefore not mounted directly on armature shaft
22, but rather on sleeve 73. Central opening 47 of armature 40
therefore accommodates armature shaft 22 and sleeve 73.
[0037] A further, fourth embodiment of a heat-conducting element is
shown in FIG. 5. Heat-conducting element 74 is tubular. It is
integral with fan wheel 60. Together with fan wheel 60, tubular
heat-conducting element 74 forms a pot-shaped configuration.
Tubular heat-conducting element 74 is connected with armature 40 in
a thermally conductive manner in that it bears against or rests on
outer circumference 49 of armature 40. Accordingly, the inner
diameter of tubular heat-conducting element 74 is essentially the
same as the outer diameter of armature 40, at least at its open end
near the armature. The open end of tubular heat-conducting element
74 therefore accommodates at least a portion of armature 40 near
end face 48 which faces fan wheel 60.
[0038] Heat-conducting element 74 is fastened to armature 40, e.g.,
using a heat-conducting adhesive mass. Tubular heat-conducting
element 74 can form a closed surface, or it can include axial slots
79. The particular advantage of a tubular heat-conducting element
74 is the fact that it enlarges the heat-dissipating surface
considerably. The surface of tubular heat-conducting element 74 can
also be enlarged by using a profiled surface instead of a smooth
surface. A profiled surface can include, e.g., ribs, which can have
any type of cross sectional design, e.g., rectangular, triangular,
or undulating. As an alternative, to enlarge the surface even
further, a tubular heat-conducting element 74 can be provided which
does not have a cross section which is smooth and round, but which
is undulating, zigzagged, or the like.
[0039] FIG. 6 shows a further embodiment of a heat-conducting
element which is connected with the armature. A tubular
heat-conducting element 75 is provided on end face 48 of armature
40 which faces commutator 25, tubular heat-conducting element 75
being slid or inserted onto armature 40. Similar to tubular
heat-conducting element 74 depicted in FIG. 5, tubular
heat-conducting element 75 has a round cross section with an inner
diameter which essentially corresponds to the outer diameter of the
armature, so that heat-conducting element 75 rests around the outer
circumference of the armature. A partial sectional view of
heat-conducting element 75 is shown in FIG. 6. A simple tubular
heat-conducting element 75 is shown in the lower half, while
axially located, impeller-like, heat-conducting surfaces 76 are
shown in the top half. Heat-conducting element 75 can be fastened
to the armature, e.g., via bonding, in a manner similar to
heat-conducting element 74.
[0040] It will be understood that each of the elements described
above, or two or more together, may also find a useful application
in other types of constructions differing from the type described
above.
[0041] While the invention has been illustrated and described as
embodied in electrical machine, it is not intended to be limited to
the details shown, since various modifications and structural
changes may be made without departing in any way from the spirit of
the present invention.
[0042] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic or
specific aspects of this invention.
* * * * *